Current progress; using a modified SVG from wikipedia.  Now playing with
the stack layouts and coordinates.
New progressbar widget.
Use the new progress bar widget, based on d3's brush thingy, to navigate
through the visualization's epochs quickly.  There are full-board
configurations in the strategies_iter array in the incoming json.  The
algorithm finds the nearest board configuration and updates to that.
Make sure the progress bar widget is included.